When the plunger on a syringe is fully depressed, a small amount of fluid stays trapped in what is known as the "dead space." By reducing the amount of dead space in the syringe design, researchers say they can reduce the amount of infectious blood trapped inside by a factor of a thousand—and thus vastly reduce the numbers of viral particles available to spread disease.

Using a simulation model, the authors found that switching to low-dead-space syringes could reduce annual HIV infections from syringe sharing to nearly zero within eight years.

Although there are still a number of barriers to making low-dead-space syringes available worldwide, the authors say this low-cost intervention could help keep drug users—and their families—disease free.